Controlling pest populations is essential to human health, modern agriculture, food storage, and hygiene. There are more than ten thousand species of pests that cause losses in agriculture and the worldwide agricultural losses amount to billions of U.S. dollars each year. Accordingly, there exists a continuous need for new pesticides and for methods of producing and using such pesticides.
The Insecticide Resistance Action Committee (IRAC) has classified insecticides into categories based on the best available evidence of the mode of action of such insecticides. Insecticides in the IRAC Mode of Action Group 1B are acetylcholinesterase (AChE) inhibitors that are organophosphate compounds. The insecticides in this class are believed to inhibit AChE, which is the enzyme that terminates the action of the excitatory neurotransmitter acetylcholine at nerve synapses, resulting in hyperexcitation of the affected insects. Examples of insecticides in this class are chlorpyrifos, malathion, parathion, acephate, azamethiphos, azinphos-ethyl, azinphosmethyl, cadusafos, chlorethoxyfos, chlorfenvinphos, chlormephos, chlorpyrifos, chlorpyrifos-methyl, coumaphos, cyanophos, demeton-S-methyl, diazinon, dichlorvos/DDVP, dicrotophos, dimethoate, dimethylvinphos, disulfoton, EPN, ethion, ethoprophos, famphur, fenamiphos, fenitrothion, fenthion, fosthiazate, heptenophos, imicyafos, isofenphos, isopropyl O-(methoxyaminothio-phosphoryl) salicylate, isoxathion, mecarbam, methamidophos, methidathion, mevinphos, monocrotophos, naled, omethoate, oxydemeton-methyl, parathion-methyl, phenthoate, phorate, phosalone, phosmet, phosphamidon, phoxim, pirimiphos-methyl, profenofos, propetamphos, prothiofos, pyraclofos, pyridaphenthion, quinalphos, sulfotep, tebupirimfos, temephos, terbufos, tetrachlorvinphos, thiometon, triazophos, trichlorfon, and vamidothion.
Although the rotational application of pesticides having different modes of action may be adopted for good pest management practice, this approach does not necessarily give satisfactory pest control. Furthermore, even though combinations of pesticides have been studied, a high synergistic action has not always been found.